Conventionally, a spark plug is used in an internal combustion engine. The spark plug has electrodes for forming a gap therebetween. For example, an electrode having a noble metal tip is used. In this connection, there is proposed a technique for welding a noble metal tip to a tip holder and welding the tip holder to a ground electrode.
In the case of using a tip holder for attaching a noble metal tip, as compared with the case of attaching a noble metal tip without use of a tip holder, the number of components increases; accordingly, appropriate attachment of the noble metal tip has not been easy. For example, a large burden has been involved in maintaining both of a dimensional tolerance of the noble metal tip and a dimensional tolerance of the tip holder within small ranges, respectively.
An object of the present invention is to facilitate implementation of appropriate attachment of a noble metal tip.
The present invention has been conceived to solve, at least partially, the above problem and can be embodied in the following application examples.